1. Field of the Invention
This invention relates to an apparatus for seamwelding cylindrical workpieces and, more particularly, to an improved apparatus which permits such seam welding to be accomplished while the workpiece is moved continuously through and between a pair of opposed electrodes.
2. Background Art
Many cylindrical objects, such as oil-filter cans and shock absorber bodies, have a resistance-type seam weld extending therearound for fixedly and sealingly securing the cylindrical side wall of the can to an end wall or the like. Such circumferential weld is conventionally performed on an intermittently movable indexing table which sequentially moves the can into position between a pair of opposed electrode wheels. The indexing table is stopped when the can is positioned between the electrode wheels, and these wheels then move inwardly to engage the can on substantially diametrically opposite sides thereof, whereupon rotation of the electrode wheels and a corresponding rotation of the can through an angle of about 180.degree. creates a seam weld which extends continuously around the can. The electrode wheels are then moved radially outwardly away from the can, and the indexing table is rotated through a further increment so as to remove the welded can and simultaneously move the next can into the welding station. While such apparatus can successfully accomplish a satisfactory seam weld on the can, nevertheless the production rate of such equipment is rather low since the incremental or stepping movement of the indexing table severely limits the rate at which cans can be satisfactorily welded since substantial time is lost between successive welding operations. This significant lost time between successive welding operations severely restricts the number of cans which can be welded per unit time, and hence severely reduces the overall production efficiency.